Constant Airlocks

[Plamber]

Hello all.

The system is an open vented system with the cold water tank 5" above the cylinder in a small cupboard so there is no way of removing them (must have been built in). it is heated by immersion heater.

The thing is, its airlocking every couple of days, the woman said its been like that for 8 years and has only now tried to get it sorted.

What i have tried so far is emptying both tank and cylender and filling up from washing machine valves, from bath taps, WHB taps and kitchen taps. getting everything working for a few days then the pressure on the hot water drops to very slow. the kitchen and bathroom are on different sides of the flat and all the pipework seems undamaged (no kinks,dents). I even had another and very experienced plumber with me today and he was confused with it. his suggestion was some kind of flange, something ive never fitted or used before.
ADVICE PLEASE.

thanks in advance


I have also increased the hight of the vent pipe as much as possible.

 

[Plamber]

my plumbing merchant doesnt seem to know about a fitting like that, although he doesnt know muchb to be honest. would it help if i tee'd in an other vent pipe firther down the hot pipe?

Also mybe some kind of flange fitting on the hot pipe just after the cylender? is there a fitting/flange that would help?

 

[payney1974]

Can you trace the hot pipe from the cylinder to all the outlets? Is it all surface as its a flat or does it go under floor? If under floor i would think there could be an airlock on poorly installed pipework?

 

[Plamber]

the pipework goes under the floor, its pretty obvious where everything is. goes down to a tee and slits left to the bathroom and right to the kitchen. but after i clear the airlock its fine for a few days to a week.

funny thing is, all hot water in the flat gets affected not just one side. could the be a blockage somewhere? i had a very experienced plumber with me one day and he was just a confused as me. he seemed sure that there wasnt a blockage.

 

[wards]

maybe a silly idea,but is the thermostat on the immersion heater set too high?could just be overheating and subsequently blowing off into header tank thus allowing air to be drawn into the system?just a thought
si

 

[Plamber]

thats something ive not checked actually, thanks wards. ill give that a try when im back next, its a long shot though.

water doesnt seem too hot though. would bubling water from the vent pipe pull in air??

 

[wards]

you have answered your own question.HTH
SI

 

[TerryH]

You should not impede the vent pipe. It should always be open.

What size is the vent; 15mm or 22mm.? I've recently come across two which were 15mm. One was my own job and I changed it to 22mm. The other was helping a mate, he left it with the intention of returning to change it after we had replaced the hwc.
He was called back due to hw flow diminishing to nothing. I suggested we change the vent to 22mm and it's ok now.
I think as the taps opened air was drawn back down the vent, past the hw take off and emptying the pipe; flow, slow flow and then no flow. The larger diameter pipe allows water to flow easily without restriction and draw down of air.

 

[Plamber]

vent pipe is 22mm. and so is every one on the housing scheme. there is about 50 flats all with the same system. if replacing the thermostat failes il see if its possible to up the pipes to 28mm from the cylinder

 

[charlie frederi]

Hello all.

The system is an open vented system with the cold water tank 5" above the cylinder in a small cupboard so there is no way of removing them (must have been built in). it is heated by immersion heater.

The thing is, its airlocking every couple of days, the woman said its been like that for 8 years and has only now tried to get it sorted.

What i have tried so far is emptying both tank and cylender and filling up from washing machine valves, from bath taps, WHB taps and kitchen taps. getting everything working for a few days then the pressure on the hot water drops to very slow. the kitchen and bathroom are on different sides of the flat and all the pipework seems undamaged (no kinks,dents). I even had another and very experienced plumber with me today and he was confused with it. his suggestion was some kind of flange, something ive never fitted or used before.
ADVICE PLEASE.

thanks in advance


I have also increased the hight of the vent pipe as much as possible.

Hi
have you tried servicing the ballvalve
or shut the cold feed to the cylinder and drain the head off
once the vent is clear of wateropen the cold fill also is the element switching off at 60 degrees ie not boiling over filling the vent with water causing air lock
or it could be there is not enough gravity to supplie areas dependent on position of taps and pipe sizes.